The present invention relates generally to fuel cells and, more particularly, to fuel cells of the hydrogen-oxygen type. Fuel cells for the production of electrical energy from a gas or liquid containing a combustible component and an oxidizing gas are well known in the art. In a typical fuel cell a combustible gas, such as hydrogen, is introduced into a cell through a porous electrode made, for example, of a noble metal or of porous carbon containing a noble metal catalyst. Oxygen or an oxygen-containing gas is introduced through a second porous electrode containing, perferably, an active metal oxide catalyst, the two electrodes being electrolytically connected through either an aqueous electrolyte solution or a solid electrolyte, for example, an ion-exchange membrane. In these cells, low voltage D.C. energy is produced directly from the reaction of hydrogen and oxygen at relatively high conversion efficiencies. Because they are light weight and portable, such sources of electrical energy are particularly suitable for military and space purposes where a ready source of electrical energy is often not available.
When such cells are used for the production of electrical power, hydrogen and oxygen are consumed to form water which dilutes the electrolyte. The water is formed in the vicinity of the hydrogen electrode and at the operating temperature of the cell easily turns into steam. In order to maintain the concentration of the electrolyte, the water vapor must be removed from the cell. Typically, this removal is accomplished by circulating a hydrogen stream containing the water vapor through a condenser where the water is liquified. Liquified water can then be pumped to water storage tanks where it will be stored for future use.
The use of a pump requires that energy from the system be expended. Because fuel cells are employed in situations where energy already is in short supply, it is imperative that energy for the pump be kept to a minimum. In addition, because fuel cells are often used in sub-freezing environments, precautions must be taken to assure that water vapor is not allowed to freeze and thus clog lines. By way of example, such a sub-freezing environment may be encountered in deep submergence applications where the water storage tank is outside the power plant containment vessel and the sea water temperature may be as low as 28.degree. Fahrenheit.